How we roll: Reducing black plastic in vegetable production
This three-year project set out to assess the efficacy of grass and legume cover-crop mulches as a substitute for black plastic mulch, which is widely used and often ends up in landfills. Rodale Institute’s Research Farm in Kutztown, Pennsylvania, along with four collaborating farms, tested the profitability and soil health benefits of different combinations of rolled, mowed, and plowed vetch and rye cover crops, with and without plastic.
Results showed that the early termination of a cover crop associated with black plastic mulch resulted in lower biomass when compared to rolled or mowed systems. The rye and rye/vetch cover crops had roughly double the biomass of the vetch cover crop. Carbon contribution of cover crops was highest in treatments that received rye or rye/vetch without plastic, nearing 50 percent more than those with vetch treatments. On the other hand, nitrogen contribution was almost 50 percent higher in treatments with hairy vetch, either singly or in mix with rye.
An ambitious outreach plan included informing 3,000 growers about the project and specifically supporting 25 farmers as they implemented a cover crop no-till system on 10 percent of their collective vegetable acreage. The goal was to reduce the farmer’s input costs by 90 percent and increase profitability by 50 percent, with the added benefits of reducing erosion, increasing organic matter, maintaining equivalent weed control, and giving the farmer comparable yield as compared with the black-plastic system.
A series of project-related field days, website downloads of project materials, web and print summaries of research results, project-specific surveys, and collaboration with Cooperative Extension educators meant that the ambitious goal of reaching 3,000 farmers actually ended up being closer to 19,000—an indirect but compelling measure of using multiple contact points and many different ways of engaging regional farmers.
The more modest target of having 25 farmers adopt the cover-crop treatment on selected acreage was verified through follow-up, and the project managers also learned that at least 160 roller/crimpers were sold to regional farmers and growers during the three-year project lifespan. “This is a testament to the adaptability of the system,” say the project leaders, and it is likely that some farmers may also have built their own roller/crimper, since the building plans were freely available on the Rodale Institute website.
The very real challenge of conducting field research while also acting as a catalyst for measurable change in farm practices took considerable planning, outreach, and project team commitment—including a commitment to the participating farmers. “The farmers attended our field days, showcased their fields, and shared the ups and downs they had, but at the end of the project they felt that there is a great potential for cover crops to replace black plastic, especially when they used the roller crimper at the right time.”
And the next step? More research on cover crop mixtures that suit the vegetable production window, and especially mixtures that provide longer weed suppression.